Questions to the employer on an interview

Recently I have read a thread concerning a question not what we will be asked on an interview but on the other hand what we should ask as an interviewee.

Some of the suggestions:

1. What time does work start and ends?
2. Which IDE and CI are used?
3. Are there any internal trainings?
4. Is unit testing used?
5. Is wiki used?
6. Which libraries and frameworks are used?
7. Are there many own libraries created?
8. Which work methodologies are used?
9. Why does previous employee quit?
10. Does work concern more maintenance or new projects?
11. What trainings are possible?
12. Are there any overtime if so how are they paid?

There is also a question which to choose as we wouldn't have time for many of them.

For me three most important are: 3,6, 10.